1. Field of the Invention
The invention is particularly concerned with filtering systems for hydraulic reservoirs and more particularly for improving such filtering systems when they are located within hydraulic reservoirs. More particularly, the invention is concerned with a particular means for arranging filters within a hydraulic reservoir which makes allowance for manufacturing tolerances whereby these tolerances can be relatively large and yet the filter means will still be effectively and relatively exactly placed within the reservoir.
2. Prior Art
The majority of prior art filters for liquid systems a illustrated for example by the teachings of U.S. Pat. No. 3,685,658 have been mounted externally of the reservoir or sump of such a system. In such a situation, one has not been generally faced with the problems encountered in mounting a filter within a reservoir. Some filter elements are also used within hydraulic reservoirs such as those disclosed in, for example, U.S. Pat. Nos. 3,886,072 and 3,900,400 but these are of considerably different structure, operation and mounting than are the srtuctures of the present invention.
One of the more important problems which occur when one desires to mount a filter within a reservoir is that the filter elements of the filter must be so mounted within the reservoir that flow must take place through them. This often introducesproblems of carefully machining parts which are to fit within the reservoir, which parts must often be machined within relatively close tolerances. Such parts must also be capable of adjusting these tolerances as both the reservoir and the elements themselves change size as the fluid being passed through the filters and into the reservoir changes temperature. This problem is especially severe when the filter elements, as in accordance with the present invention, are held within a tube which is supported at each end by a pair of parallel walls of the reservoir since any difference in thermal expansion or contraction of the tube as compared to any expansion or contraction of the reservoir must be compensated for. Such problems do not occur for example in such liquid filters as are taught in U.S. Pat. No. 3,685,658 wherein a spin or thread-on type of filter and it's operation are disclosed.
The present invention provides filter means internally of the reservoir which are attached longitudinally between a first and second generally parallel wall of the reservoir and which includes a tube extending between said first and second wall of the reservoir, said tube having filter elements therewithin. Most particularly the present invention solves the problem of making such tubes fit properly within the reservoir without the requirement that the size of the tube be carefully held to very specific and small manufacturing tolerances and which further provides automatic adjustment for significant differences in the thermal expansion of the tube and of the tank of the reservoir. This and other advantages of the invention as will become apparent from the following description are accomplished by the invention as disclosed and claimed herein.